Not sure anyone has yet commented on the stacking vs side-by-side since the title was recently revised. I would only recommend the stacking units if you have limited space in the laundry room. There is usually some amount of vibration during washing and having the extra weight of the dryer on top could lead to other issues. I assume in that configuration the dryer would be on top? If space isn't an issue, I would always recommend the side-by-side models.